Dec 7 (Reuters) - Sage Therapeutics Inc said on
Thursday its drug to treat patients with moderate to severe
depression met the main goal of reducing symptoms in a mid-stage
study, sending its shares soaring 52.3 percent in premarket
trading.

The 89-patient study testing the drug, SAGE-217, showed
statistically significant reduction of depression symptoms, when
compared to a placebo.

Depression is a common mental illness characterized by
persistent sadness and a loss of interest and lack of ability to
do everyday activities and work.

The drug was granted fast-track designation by the U.S. Food
and Drug Administration in May, the company said.

Patients were assessed on a scale that rated the severity of
their depression symptoms such as mood, feelings of guilt,
suicidal thoughts and insomnia.

Sage's postpartum depression drug succeeded in two
late-stage studies in November, paving the way for it to bring
to market the first FDA-approved treatment for the disorder.